Throughout both his record-breaking PRIDE and Shooto championship reigns, Gomi was considered to be the top Lightweight fighter in the world.[4] Due to his domination of PRIDE Fighting Championships's Lightweight division, Gomi is regarded as one of the greatest Lightweight combatants in the history of the sport.[5][6][7]

Gomi was born in Kanagawa, Japan in 1978 and started boxing at Sagamihara Yonekura Gym in 1994 while he was attending Kanagawa Prefectural Aikawa Higashi Junior High School. Gomi was athletic and the pitcher of the school's baseball team, but dropped out of high school in 1996 when he failed to pass on to the next grade. This caused an argument between Gomi and his father who disowned him as a result of the incident. Gomi then went on to learn freestyle wrestling and catch wrestling at Kiguchi Dojo and competed in many wrestling tournaments throughout Japan, the pinnacle of his grappling career being his four All-Japan Combat Wrestling championships, in which he defeated a number of the nation's top grapplers, future opponent Mitsuhiro Ishida amongst them.[citation needed]

Gomi joined the official Shooto gym in 1997 where he began training and taking part in the amateur Shooto competitions. He made his professional mixed martial arts debut on November 27, 1998 at Shooto Las Grandes Viajes 6 in Tokyo, where he defeated Hiroshi Tsuruya by decision. Gomi won his first 14 MMA matches, mostly in the Shooto organization, but also fought in Vale Tudo Japan and in the Hawaiian-based organization SuperBrawl.

Gomi's first loss was also his last fight in Shooto for six years. It took place on August 10, 2003 at the Yokohama Cultural Gymnasium. Gomi lost his title to Norwegian fighter Joachim Hansen by majority decision. This loss was considered a huge upset at the time due to Hansen's 6–1–1 record in MMA.

After back-to-back losses, Gomi found a new home in Japan's biggest MMA organization, the PRIDE Fighting Championships. He made his debut within the organization on February 15, 2004 at PRIDE Bushido 2 where he fought Jadyson Costa of the famed Chute Boxe team out of Brazil. Gomi stopped Costa via TKO halfway through the first round.

Gomi was asked back to PRIDE to face off with the undefeated Ralph Gracie at PRIDE Bushido 3. Gracie was the first coach of B.J. Penn, one of Gomi's losses. Unlike his fight with Penn, Gomi made quick work of Gracie, scoring a six second KO in the first round, the quickest match in the organization's history, due to repeated knee strikes.

Gomi started off 2005 with a win over Luiz Azeredo at PRIDE Bushido 7. Azeredo dominated the fight from the opening bell with knees, punches, and flying kicks, but at the 3:46 mark of the first round, Gomi caught Luiz with two hooks that sent the Chute Boxe fighter to the mat. Gomi was then criticized for continuing to attack, even after Azeredo became unconscious, and was restrained by Dream Stage Entertainment (DSE) crew and staff. The Chute Boxe team stormed the ring and got into an altercation with Kiguchi Dojo. Gomi later stated that the extracurricular attack was due to adrenaline and apologized for his actions.

In August, PRIDE announced that in the month of September they would be hosting an eight-man Lightweight tournament. The first round set up Gomi with fellow Japanese fighter and then Shooto World Lightweight ChampionTatsuya Kawajiri. This fight was billed "the battle of the twenty first century boys" in Japan due to the popularity and world-class match up of the two fighters.[citation needed] Many MMA critics had Gomi ranked number one and Kawajiri number two in the Lightweight division.[citation needed] Gomi submitted Kawajiri in the first round with a rear-naked choke. Gomi then had to fight again later that night in the semi-finals against Luiz Azeredo. Gomi won via unanimous decision, becoming a finalist in the 2005 Lightweight Grand Prix.

Gomi met the other finalist, Hayato Sakurai, at PRIDE Shockwave 2005. Sakurai and Gomi were teammates at the official Shooto gym back in the late 90's.[citation needed] Sakurai defeated Jens Pulver and Joachim Hansen to reach the finals. After some exchanges on their feet, Sakurai tried to take Gomi down with a hip toss, but on the way down, Gomi ended up on top in the mount. "The Fireball Kid" began to rain down punches, and after taking many shots Sakurai twisted to escape, giving his back to Gomi. Finally Sakurai escaped and both fighters were on their feet, but the punches had taken their toll on Sakurai. Gomi threw a right hand and then followed up with a left-right combination. The last right hook caught Sakurai on the chin, knocking him out at 3:56 of the first round. Gomi was crowned the PRIDE 2005 Lightweight Grand Prix Champion. The KO win helped Gomi earn 2005 Fighter of the Year honors from Sherdog, an honor he shared with Mauricio "Shogun" Rua.

Gomi then made his 2006 debut at PRIDE Bushido 10. Before the event, DSE announced that Gomi would be crowned the PRIDE Lightweight Champion due to winning the PRIDE 2005 Lightweight Grand Prix, although the upcoming Bushido 10 fight would not be a title match. He then faced Marcus Aurelio of American Top Team later that night. Aurelio choked out Gomi within the first round with an arm triangle. This match-up was a huge upset and put doubt within Gomi's ability to fight off of his back. Although Aurelio won the match, it was a non-title bout, with Gomi remaining the PRIDE Lightweight Champion. Gomi said he took the match too easily and that this loss was the best thing for him to refocus and become a better fighter.[citation needed]

After a few months off while building his Rascal Gym, Gomi made his return to the PRIDE ring at PRIDE Bushido 12 against 10–1 French fighter David Baron. Baron seemed willing to trade with Gomi and managed to slip some punches. Eventually Gomi caught up with him and knocked the Frenchman down, mixing up punches to the head and body. Baron missed a takedown attempt, allowing Gomi to get around his back and slam Baron to the ground. Baron rolled in an attempt to shake off his Japanese opponent, but Gomi held on, sinking in a rear-naked choke. Baron defended the choke as long as he could, but eventually Gomi completed the technique, forcing Baron to tap at the 7:10 mark of the first round. Baron had previously won a tournament in Europe for the right to face Gomi.[citation needed]

Gomi rematched Aurelio at PRIDE Bushido 13 on November 5, 2006. This time the PRIDE Lightweight Championship was on the line. Both fighters were extremely cautious, and many times the referee could be heard calling for more action during the bout. Aurelio's jab was effective and hit the champion several times. Gomi, often switching his stance, replied with strikes of his own and landed numerous leg kicks. Several times the American Top Team fighter ended up on his back after failed takedown attempts. Rather than follow him down, Gomi just kicked Aurelio's legs until the referee would stand the action back up.

Aurelio scored a clean takedown at the end of the first round, though. Aurelio attempted another takedown in the second, only to see "The Fireball Kid" counter with a kimura. Gomi showed shades of his past catch wrestling accolades when he countered another Aurelio takedown attempt with a half-nelson. He did not follow Aurelio to the ground, instead attacking his legs with kicks. Gomi refused to follow Aurelio to the ground despite his opponent's taunting. Gomi knocked down Aurelio with a body shot late in the last round, and the bout ended with Gomi connecting with a hard kick to Aurelio's body just before the final bell. The fight went to the judges and Gomi retained his title, walking away with the split decision.

Gomi's earned a first round knockout against Mitsuhiro Ishida at PRIDE Shockwave 2006. Less than a minute into the fight Gomi countered a right leg kick from Ishida with a straight left punch that knocked him down. Gomi immediately went in for the finish, stopping Ishida with a series of hammer fists.

At PRIDE 33, Gomi suffered a loss to UFC veteran, Nick Diaz by way of gogoplata submission. In the beginning of the first round, Gomi was landing blows on the taller Diaz, even scoring a knockdown, which he was unable to capitalize upon. However, Diaz came back quickly and began to bombard Gomi, who had become visibly exhausted, with straight jabs and right hands for the later half of the round. As the second round opened, Gomi gamely tried to regain lost ground, but after a double leg takedown into Diaz's guard, suddenly found himself in a gogoplata submission. The lightweight champion tapped out at 1:46 of the second round. However, the Nevada State Athletic Commission has declared the fight a "no contest" after Diaz tested positive for marijuana.[8]

After Zuffa, the parent company of the UFC, purchased PRIDE Fighting Championships from Dream Stage Entertainment, Gomi signed on with World Victory Road, and fought in its inaugural event, "Sengoku", where he defeated Duane Ludwig by TKO (cut).[9]

He then fought at World Victory Road's Sengoku 4 on August 24, 2008 against Sung Hwan Pang. Gomi won the contest via Unanimous Decision. Gomi competed on November 1, 2008 where he lost a split decision to Russian fighter Sergey Golyaev at Sengoku VI. It was the Upset of the Year for 2008 according to Sherdog.com.[10] He then fought Satoru Kitaoka on January 4, 2009 for the Sengoku lightweight championship. Gomi was defeated at 1:41 by Achilles lock.

On May 10, 2009, he returned to Shooto at Shooto: Tradition Final where he faced the Shooto Champion at the time in a non title bout, Takashi Nakakura.[11] Gomi won via KO in the second round.

On January 1, 2010, it was announced that Gomi had signed with the UFC.[14] Gomi faced Kenny Florian in his UFC debut at UFC Fight Night 21 and was submitted by Florian via rear-naked choke in the third round after being dominated by jabs and body shots for two rounds.[15]

Gomi was expected to face Joe Stevenson on August 1, 2010 at UFC Live on Versus: 2.[16] However, Stevenson suffered an injury while training and was replaced by Tyson Griffin.[17] Gomi defeated Griffin via one punch KO at 1:04 of the first round. Gomi caught Griffin with a left cross following up with a right hook causing Griffin to fall face first into the canvas where Gomi then followed up onto Griffin's back with few short punches before the fight was stopped. He is the first person to have stopped Griffin via knockout as all of Griffin's previous losses have gone to a decision. Gomi also was awarded Knockout Of The Night bonus for his performance.

Gomi faced Clay Guida at UFC 125. After a very one-sided first round, he was defeated by Guida via guillotine choke in the second round.

Gomi faced Nate Diaz on September 24, 2011 at UFC 135 where he lost late in the first round by submission due to an armbar.[18]

Gomi was expected to face George Sotiropoulos on February 26, 2012 at UFC 144 but the Australian fighter pulled out after sustaining an injury. Gomi instead faced Eiji Mitsuoka[19] and won via TKO in the second round.

Gomi defeated Mac Danzig via split decision on November 10, 2012 at UFC on Fuel TV 6.[20] Gomi, keeping true to his plead, came into the fight in considerably better shape and showcased a drastically improved game including taking Danzig down a few times.

Gomi faced Diego Sanchez on March 3, 2013 at UFC on Fuel TV 8.[21] Gomi lost a controversial split decision to Sanchez. 12 of 12 media outlets scored the bout in favor of Gomi.[22] Even UFC President, Dana White, had expressed on Twitter that he felt Sanchez did not do enough to win the decision.